1. Field of the Invention
The present invention relates to a method of manufacturing an electron-emitting device. In addition, the present invention relates to a method of manufacturing an electron source including a plurality of the devices and a method of manufacturing an image display device constituted by using the electron source including the plural devices and an image-forming member.
2. Related Background Art
In recent years, an image display device having self-luminous electron-emitting devices arranged in matrix on a rear plate has been proposed. There are conventionally known two main types of electron-emitting devices: one using a thermal electron-emitting device, and the other using a cold-cathode electron-emitting device. Examples of the cold-cathode electron-emitting device include a field effect type electron-emitting device (hereinafter, referred to as “FE type”), a metal/insulating layer/metal type electron-emitting device (hereinafter, referred to as “MIM type”), and a surface conduction electron-emitting device.
Up to now, in the surface conduction electron-emitting device, an electron-emitting region has been generally formed by carrying out an energization operation called “forming” on an electroconductive thin film prior to electron emission. That is, the forming means that a DC voltage or an extremely slowly rising voltage is applied to both ends of the electroconductive thin film for energization to locally destruct, deform, or alter the electroconductive thin film, whereby the electron-emitting region brought into an electrically high resistance state is formed. In the surface conduction electron-emitting device which has been subjected to the energization forming operation, when a voltage is applied to the electroconductive thin film to allow a current to flow through the device, electrons are emitted from the electron-emitting region. Disclosed in Japanese Patent Application Laid-Open No. 2002-216616, for example, is an image display device using such surface conduction electron-emitting devices.
In addition, Japanese Patent Application Laid-Open No. H09-274847 (which corresponds to EP A1 789383) discloses a method of manufacturing an electron-emitting device, including checking on whether a foreign matter exists on a precursor film of an electroconductive thin film or not, and a method of manufacturing an electron-emitting device, including, when the foreign matter is adhered to the electroconductive thin film, removing from a substrate the electroconductive thin film to which the foreign matter is adhered and forming an electroconductive thin film on the substrate once again.
Meanwhile, in an image display device, electrons emitted from an electron-emitting device are accelerated to enter an image-forming member made of phosphor or the like, thereby obtaining luminance. Since the image display device responds in accordance with an input signal, it is necessary to electrically separate the electron-emitting devices from each other. For this reason, an insulating substrate is generally used in the image display device. However, when a surface of the insulating substrate is exposed in the vicinity of the electron-emitting region, a potential generated at the surface becomes unstable, which leads to instability in electron emission.
Upon application of a high voltage to the phosphor of the image-forming member, a potential is generated at the insulating surface in the vicinity of counter electron-emitting devices owing to capacitance division determined based on a dielectric constant of free space and a dielectric constant of an insulator. The more satisfactory insulating property the potential has, the longer its time constant becomes. Therefore, the electrostatically charged state of the surface is maintained. When electrons are emitted from the electron-emitting device in this state, the electrons collide against the electrostatically charged insulating surface as well. In this case, the electrons are accelerated, and when electrostatically charged particles such as electrons or ions are ejected into the insulating surface, secondary electrons are generated. In particular, abnormal electrostatic discharge is caused under the high electric field, and accordingly electron emission characteristics of the device decrease significantly. In the worst case, the electron-emitting device would be destroyed.
An influence caused by the electrostatic charge on the insulating surface becomes more prominent as a distance to an electron emission point is smaller. Thus, it is necessary to suppress the electrostatic charge especially in the vicinity of the electron-emitting device. As a means for coping with this, Japanese Patent Application Laid-Open No. 2002-358874 discloses a method in which an antistatic film is formed in the vicinity of the electron-emitting device by spraying a solution prepared by dispersing electroconductive fine particles in an organic solvent for coating.